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1.
激光吹气是主动性研究等离子体内部杂质输运的最佳方法之一。杂质的注入用杂质粒子流表示 Г=-DVn+Lvn 式中,D为输运系数,V为对流速度。激光吹气实验可在放电中选择不同时段注入可控量的杂质。由于杂质注入量很小且附加脉冲信号持续时间很短,等离子体电流和温度都没有明显扰动。杂质约束时间可根据中心道信号衰减时间来计算。  相似文献   

2.
采用高Z杂质注入HL-1M等离子体中, 触发等离子体电流衰竭的实验已经施行.用激光吹气注入高Z杂质能够增加辐射冷却,等离子体在-3ms时间内迅速冷却而且在电流终止之前电子温度损失约80%.实验证明:它是一种使得大型聚变实验装置上在放电破裂之前显著减少等离子体中热能而且安全终止放电的简单、快速和有效的途径. 关键词: 高Z杂质 破裂 等离子体终止 激光吹气  相似文献   

3.
在聚变堆条件下,等离子体中杂质将严重影响燃料的浓度,并产生大量的功率损失而倍受关注。普遍用于托卡马克等离子体杂质输运研究的方法是瞬态扰动法,主要以主动注入杂质源来研究杂质的扩散和对流过程。短脉冲型的杂质注入一般可采用快过程的压电阀和激光吹气两种方式,而激光吹气方法是一种不容置疑的最好的杂质输运研究方法,因为杂质的注入时间和注入量都可以得到很好的控制,几乎能研究任何状态的等离子体杂质输运过程并对等离子体参数的扰动最小。杂质输运信息可通过探测杂质离子的辐射来得到,这些辐射主要包括由光谱仪测量的线辐射信号和由软X射线成像技术得到的软X射线辐射信号,通过这些测量可带出杂质分布的空间和时间演化的信息,再利用数值模拟计算编码,重建实验数据,从而得到杂质输运的扩散系数D、对流速度V和约束时间等。  相似文献   

4.
HL—1M装置几种杂质谱线的特性   总被引:1,自引:0,他引:1  
介绍了HL-1M装置真空紫外光谱区的杂质辐射观测结果。对器壁硅化后的杂质特性进行了分析,用激光吹气技术研究了杂质输运,分析了低混杂波电流驱动、弹丸注入实验中杂质谱线的变化。  相似文献   

5.
HL-2A装置MHD不稳定性实时预测破裂系统采用了一种简单有效的方法来预测MHD不稳定性导致的等离子体大破裂。利用Mirnov线圈探测MHD信号,根据信号的振幅或频率特点设定计算方法,来预测等离子体破裂先兆,然后用激光吹气注入杂质来缓解等离子体破裂。研究结果表明,该系统能够实时预测破裂先兆,按量注入杂质后,可达到破裂缓解目的。  相似文献   

6.
在欧姆放电和低杂波电流驱动(LHCD)及激光吹气注入杂质的联合实验中,首次在HL-1M 装置上观测到了与软X射线对应得非常好的锯齿型密度振荡。这种类锯齿型的密度振荡存在于低杂波电流驱动与激光吹气等离子体中。分析表明,该锯齿不是通常的q = 1 有理面上的锯齿,而是在低杂波与杂质共同作用下产生的类锯齿型的密度振荡。一种可能的机制是低杂波电流驱动下杂质的中心积累及崩塌引起的扰动磁场导致了快电子的损失,从而使得密度发生振荡  相似文献   

7.
HL-2A和HL-1M装置采用了激光吹气注入高Z杂质来缓减大破裂中的等离子体电流衰竭,并给出了初步实验结果。在HL-2A装置上建立了利用MHD扰动的参量预报放电破裂先兆的报警系统,研制了MHD实时检测与处理系统,实现了放电破裂先兆的预报、快速触发激光吹气、形成阻性高辐射等离子体、消耗热能和磁能,缓减大破裂。实验证明,这是一种使得大型聚变实验装置在放电破裂之前显著减少等离子体中热能和磁能,而且能安全终止放电的简单、快速和有效的途径。  相似文献   

8.
激光吹气技术在HL—1M等离子体中的应用   总被引:4,自引:2,他引:2  
本文叙述了在HL-1M中用激光吹气技术进行的金属杂质实验及杂质输运特性的研究。  相似文献   

9.
在欧姆放电和低混杂波电流驱动条件下,应用激光吹气技术注入金属杂质,用真空紫外谱仪测量了杂质线的辐射,给出了HL-1M 装置欧姆等离子体和低混杂波电流驱动等离子体杂质输运的研究结果。用杂质输运程序LBO进行数值模拟,得出了等离子体中杂质的扩散系数D(r) 和对流速度v(r)。在低混杂波电流驱动条件下,等离子体杂质的输运系数相对欧姆放电等离子体杂质的输运系数减小了50% 左右。结果表明,在HL-1M 装置上低混杂波电流驱动等离子体相对通常欧姆等离子体杂质的约束性能明显得到了改善  相似文献   

10.
使用十六道探测器阵列在HL1M装置上对中性束加热等离子体中注入氢丸和铝杂质的辐射损失功率进行了测量。通过对测量数据的分析,获得了以下主要实验结果:(1)中性束加热等离子体辐射损失功率密度分布在等离子体小半径(35)a范围内较平坦,辐射功率密度为0.1W·cm-3左右;(2)在中性束加热期间,用激光吹气注入铝杂质,辐射损失功率密度增加了1倍,但它的分布不明显峰化;(3)注入的氢丸使等离子体辐射损失功率密度增加了2倍多,且辐射损失功率密度分布显著峰化。  相似文献   

11.
Transient perturbation methods are most appropriate to study particle transport in tokamaks. Two most commonly used techniques of impurity injection are laser blow-off and gas puffing. The laser blow-off injection technique is undoubtedly the best one to study impurity transport because the injection time and the alnount of injected material can be controlled in a certain phase of the discharge with a minimum perturbation of the plasma parameters. The information of the impurity transport is obtained from the detection of emission of injected impurity ions located in different spatial regions. The radiation includes line emission, soft X-ray emission and plasma global radiation.  相似文献   

12.
Small amounts of metallic impurity is injected by laser blow-off on HL-2A tokamak in order to study transport phenomena. The particle transport is interpretated along  相似文献   

13.
Transient perturbation methods are most appropriate to study particle transport in tokamaks. Two most commonly used techniques of impurity injection are laser blow-off and gas puffing. Short bursts of impurities, injected using the laser blow-off injection technique, are among other transient perturbation methods, undoubtedly best suited to study impurity transport The injection time and the amount of injected material can be controlled in order to study a certain phase of the discharge with a minimum perturbation of the plasma parameters. Furthermore, the source is of very short duration and thus provides an experimentally more direct measure of impurity transport.  相似文献   

14.
By using of a six-channel HCN laser interferometer, the sawtooth-like density oscillations without being exhibited in the ohmic phase plasma have been observed during lower hybrid current drive (LHCD) discharges in the HL-1M device. There are often accompanied by injected impurity with laser blow-off. Analyses show that this kind of density sawtooth-like oscillation comes from the mutual effect of LHCD and impurity. An available mechanism is the loss of superthermal electrons by the magnetic perturbation, which is caused by the crash of the central accumulated impurities.  相似文献   

15.
Impurity transports in two neighboring discharges with and without electron cyclotron resonance heating(ECRH)are studied in the HL-2A tokamak by laser blow-off(LBO) technique.The progression of aluminium ions as the trace impurity is monitored by soft x-ray(SXR) and bolometer detector arrays with good temporal and spatial resolutions.Obvious difference in the time trace of the signal between the Ohmic and ECRH L-mode discharges is observed.Based on the numerical simulation with one-dimensional(1D) impurity transport code STRAHL,the radial profiles of impurity diffusion coefficient D and convective velocity V are obtained for each shot.The result shows that the diffusion coefficient D significantly increases throughout the plasma minor radius for the ECRH case with respect to the Ohmic case,and that the convection velocity V changes from negative(inward) for the Ohmic case to partially positive(outward) for the ECRH case.The result on HL-2A confirms the pump out effect of ECRH on impurity profile as reported on various other devices.  相似文献   

16.
The blow-off of Al targets from a transparent support by single pulses of intense laser irradiation through the support is investigated for target thicknesses up to some m. The blow-off process is theoretically described by calculations of the phase front dynamics in the target, adopted from Harrach's analytical solutions for laser heating and burnthrough of opaque solid slabs. Experimentally two laser beam sources were used: a Nd:YAG laser with a Gaussian intensity profile and a Nd:Glass-laser system with a homogenized flat-top profile. Two types of removal mechanism could be identified. In the first mode (low laser intensities and/or thin targets) the target is completely molten and can easily be blown-off by the vapor originating at the target-support interface. In the second mode (high laser intensities and/or thick targets) superheating of the liquid Al or a burst of the remaining solid layer of the target occurs. In both cases in the second mode the blow-off process is characterized by higher vapor pressures.  相似文献   

17.
Yu X  Peng J  Sun R  Yang X  Wang C  Sun J  Li X  Jia B  Zhao Y  Chen D 《Optics letters》2012,37(11):2106-2108
The influence of femtosecond laser-induced plasma (FLIP) on the stability of a premixed CH(4)/O(2)/N(2) flame is investigated at atmospheric pressure. The laser energy, laser repetition rate, the equivalence ratios, and the volume percentage of oxygen in O(2)/N(2) blends are varied. Our findings indicate that the flame blow-off velocity is a function of these parameters. It has been experimentally found that the flame blow-off velocity increases by a factor of two with FLIP than without FLIP. A high-repetition-rate and a great energy laser-induced plasma flameholding, as a non-intrusive optical flameholding, may be a feasible alternative for any combustor.  相似文献   

18.
在HL-lM装置上利用激光吹气技术,在等离子体边缘瞬态注入少量Al杂质粒子,通过对真空紫外光谱和软X射线区的杂质辐射测量,分别研究了欧姆等离子体和低杂波电流驱动等离子体两种情况下,Al杂质粒子输运与约束特性。结果表明:在欧姆等离子体和低杂波电流驱动等离子体两种情况下,等离子体中心区,在没有MHD锯齿震荡和有MHD锯齿震荡非锯齿破裂期间,杂质粒子输运基本上受新经典规律支配;在有MHD锯齿震荡锯齿破裂期间,杂质粒子输运受MHD不稳定性支配,但其时间很短(通常小于300μs),所以在这种情况下,杂质粒子输运的平均效应比新经典值稍大。而约束区杂质粒子输运则比新经典的值大很多,是反常的。在一定条件下低混杂波电流驱动可以改善等离子体粒子约束。  相似文献   

19.
楼祺洪  陈叔琦 《光学学报》1994,14(4):37-341
采用光偏转法研究气体中准分子激光与石墨和铜相互作用产生等离子体羽的特性。用空间和时间分辨的光偏转信号分析了等离子体羽的漂移速度和膨胀速度,并从光偏转信号中测得了物质波前面的激波速度。  相似文献   

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